This is the motorcycle the U.S. Army went to war on during World War II. It is a 750cc flathead v-twin, affectionately known as the "45." Harley made tens of thousands of these machines during the war, but unlike Indian, Harley continued to make civilian machines. When the was ended, Harley had kept its civilian dealer network and customer base intact. Indian did not, and Indian had a tough go of it after the war. Indian finally went under.
The Harley Davidson version became known as the XA-750.
Harley built about a thousand of these machines, none of which ever saw military service. By the time this motorcycle came on the scene, the U.S. Army had already fallen in love with the Jeep.